Electric motor control system



Oct. 7, 1952 J. c. RYDER ELECTRIC MOTOR CONTROL SYSTEM 3 Sheets-Sheet 1 Filed May 20. 1949 Nm Om INVENTOR.

JAMES c. RYDER ATTORNEY Oct. 7, 1952 J. c. RYDER ELECTRIC MOTOR CONTROL SYSTEM 5 SheetsSheet 2 Filed May 20, 1949 mm mm m 0N ON 00 NM .0 3 5 mm INVENTOR.

JAMES C. RYDER ATTORNEY Oct. 7, 1952 J. c. RYDER ELECTRIC MOTOR CONTROL SYSTEM 5 Sheets-Sheet 5 Filed May 20, 1949 .0m 3 g Q. S 2. 3 mm 1 H| H1 .VF 00 I M Q. mm mm 2. wm W bh 5 6 q 2. mm mm B 2. cm no on mm NF 2. 1 i m INVENTOR.

JAM ES C. RYDER N R M T Y B second washer, a second J-box, a washer saturator, and finally to a hand truck for further disposal. During this relatively extensive series of cloth treatments, the moving material is moistened and/or wetted and usually is subjected to the action of chemicals such as caustic or peroxide. These factors tend to shrink the fabric being processed, both widthwise and longitudinally. Shrinkage in length becomes a problem, because tension is required to pull or move the fabric through the processing apparatus, and with the concomitant longitudinal shrinkage caused by chemicals and/or moisture, as described, the normal amount of tension is thereby increased and magnified, often above and beyond satisfactory limits. This difficulty is often acute in the bleaching or other treatment of rayons, which have an inherently low wet strength and in the moist state are subject to tearing under excessive strains 01' tension.

The present invention, therefore, contemplates means for preventing undesirable tension in textile material as, for example, by establishing and maintaining slack therein during a pre-determined part or portion of its travel lengthwise through a continuous range of operations. To that end, there is proposed a control unit or controller device suitably mounted in or adjacent the range of treating apparatus and adapted to alternately retard or advance within pre-determined limits, as may be required, the speed at which a continuously moving length of material passes a given point in the range.

More particularly, a loop may be established as the moving textile material passes at a given or constant rate of travel from one machine or apparatus to another, say, for example, from the squeeze rolls at the delivery end of a saturator to an adjacent J -box steamer. This loop may be suspended at its opposite ends from reels on the adjacent machines. Its depth, that is the specific amount or degree of slack in the loop, is controlled between predetermined upper and lower limits. When the bottom of the loop reaches or contacts the lower limit, a ratchet relay is actuated to cut in extra resistance in the field of a variable speed D. C. shunt motor (if that particular type of motor be employed), controlling the rate at which the material passes through the exit portion of the loop, thereby speeding up the motor and the passage of the material at that point, and decreasing the depth of the loop. Thus the extent of the loop or the amount of slack in the moving material is gradually reduced until a predetermined upper limit is reached. At that time, by contact of the material with the upper limit, the relay operates again and is actuated to.cut out the extra resistance, thereby slowing up the variable speed motor and causing the loop to drop gradually or increase its depth to increase the amount of slack in the fabric or material. Thus there is provided controller means for continuously moving the fabric from one station to another in the slack condition in combination with means for adjusting the amount or degree of slack therein.

The operation of the ratchet relay above mentioned is controlled electronically. A second relay is in the plate circuit of a cold cathode tube.

The starter anode circuit is broken and one side trol from one electrode to the other as the loop rises and falls. As the cloth comes in contact with one or the other of these electrodes, the starter anode circuit is completed, thus firing the tube and causing it to conduct. The relay in the plate circuit then closes, operating the ratchet relay which performs a double function, namely, it changes the resistance of the motor field, causing the speed of the variable speed motor to change, and it also transfers control from one to the other of the limiting electrodes, at the same time extinguishing the tube and opening the plate circuit relay. Furthermore, means are provided, as willbe apparent, to insure that the ratchet relay has sufiicient time to make a. complete cycle.

Referring now to the drawings:

The present invention may be employed in advancing a continuously moving length of textile material 10 in web, rope or other form, from between the squeeze rolls -42 of a saturator (not shown). A constant speed motor I3 may be mounted near the squeeze rollers l|-l2 to move the web It! at a uniform rate of speed from the rollers l |l2 of the saturator over a reel 14, also driven by the motor [3, into the zone where the present controller is effective to establish and maintain a loop 35 in the moving cloth I 0 within the pre-determined upper and lower limits it and l! respectively. Both limits I 6 and I! may be made of metal or other suitable material and constructed in the form of horizontally mounted and aligned fixed bars or metal idler rollers extending in spaced relationship laterally above and below the moving web [0. Preferably, the lower limiter electrode may be constructed in the form of a U-shaped pan which prevents the cloth descending to the floor when the apparatus is not in use. To prevent sudden increases in tens'ion when the cloth touches the upper limit [6, the latter may be yieldably supported, so that it is capable of vertical movement or displacement upon contact with the cloth to. If desired, a limit switch (not shown) may also be provided to shut down the range should the displacement of the upper limit or electrode exceed a predetermined amount.

Limits IS and l! are preferably electrically insulated from their supports and are connected through leads l8 and 19 respectively to an auto matic controller 20. The controller 20 is connected through lead 2| to an idler roll 22. Thus the cloth l0 when it touches either limit It or I! may complete the circuit with the controller 20 and cause it to operate.

, The controller 20 is connected through leads 23 and 24 to a suitable A. C. supply (as shown), and through leads 26 and 2'! to the field circuit of the motor 25. The controller 20, when activated by the cloth l0 acting through limits IE or I! and idler reel 22, functions to vary the resistance in the field circuit of the motor 25, varying its rotational speed. Further adjustment of the speed of the motor 25 is provided by the manual controller 28, a conventional variable resistor, connected by leads 26 and 29 to the automatic controller 20 and the line 3| respectively. Lines 30 and 3| represent a suitable D. C. supply for the motor 25. Lead 32 connects the armature circuit of the motor 25 to the D. C. supply line 3|. As the cloth leaves the loop 1'5, it passes over the idler roll 22, and then on to the reel 33 and the plaiter 34, both driven by the variable speed D. C. shunt motor 25. From the plaiter 34, the cloth passes down in uniform plaits or folds into a steam J-box (not shown).

It is the motor 25, controlled by the device herein described, which-is effective to maintain theslack loop 'l5 whiletranspcrting' the cloth f0 through the apparatussh-own. As shown irr'Fig. 2., the motor 251s supplied from a suitableD. 0. supply indicated-"by lines and 3+. The field winding ofthe'mot'or 25 is-connected iniseries with the :fixed resistance 36 and the manually adjustable controller, or resistor 28. The resistance 36 is connected atone-end throughth'e lead 311 to the flexiblecontactstrip 18 0i ratchet relay 4|, part of auto-controller 2-0; at-theother end it is connected through the lead 36 'to'the stiff contact strip '19 of the ratchet relay ll". Thus when the flexible contact strip 16- and the "stiff contact strip 19 of the ratchet relay 4| are closed, the resistance 36' is short" 'circui-ted or shunted out; when the flexible contact strip 18 is in the open position, the resistance 36 is efiective in the field circuit of the motor 25.

The "principalparts' of the present controller 20 include the cold cathode tube 42, the relay 43 and the ratchet relay 4|. I e

The cold cathode tube- 42 is of the t'ypewhich Will pass a current from the cathode -44 to the plate or anode 45- only when the starter anode circuit is complete (including a suitable supply).

Relay 43 is of the conventional electromagnetic normally-open type with a single set of contacts 41 and 48 which remain open except when the coil 49 is energized. A condenser 50- is connected across the coil 46 to stabilize the voltage, and to keep relay 43* closed long enough to per- 'mit the ratchet relay 41 to make afull stroke.

relay 43 are closed; at other times they remain open. The contacts 41 and 48 when closed complete the circuit including the A. 0. supply lines 23 and 24 and the coil-53 of the ratchet relay 4|.

The ratchet relay 4| as indicated in Fig. 2 and shown in detail in Figs. 3, 4 and 5, employs an electromagnet together with a ratchet mechanism so constructed and arranged that eachtime the coil is energized the contacts are moved from one to the other of two alternate positions." An electromagnet 54,- fixedly supported on base plate 55 with its axis perpendicular to the plane of the base, is energized by the coil '53, and acts asse s when at rest is almost perpendicular to the efihctthe armature-56. The shaft as is rotatably supported parallel to the base 55" and "itand thearmature 56, at points "61 and 58 by the fixed support 69. The axis of the shaft 56 is perpendicular to the plane in which the axis of the armature 56 moves. Ratchet-wheel lilis'fixedly mounted on shaft 66 at a "point directly opposite the armature 56 so that when the armature 56 is acted on by the electrdmagnet 54, it moves toward the shaft 66,

on the armature 56.- The latter is pivotally supported at 51 by the upright 58, which is fixedly supported by and perpendicular to the base 55. The supporting point 51 is near, but'not at, one end of the armature 56, so that both ends of the armature are capable of motion toward or from the base 55. A vertically disposed spring 59. one end of which is secured to a projection of the upright 58,- a'cts on one end of the armature 56 to pivot it about the point 51 andmoveit away from the magnet 54 when coil 53 is deenergized. An arm 60' projects atrig-ht angles from the upper end of the upright 58, to limit the motion of the armature 5'6.

A pawl 6| is pivotally' supported at points 5| and 52 on the end of the armature 56 opposite that which is acted on by spring 59. A horizontally disposed spring 63, fixed at one end to a projection 64 on the armature 56, holds the pawl against the guide 65 which projects perpendicularly from the armature 56 at a point near the pivot points 5| and 52 so that the pawl 6| and. the pawl 6 l engages the ratchet wheel 10, causing itto rotate andin turn rotate the shaft '65. extension of the projection 64 also eng'ages'the ratchet wheel 10 when the armature is at the-Glider its'stroketow'ard'theshaft 56 and the el'ectroma-gnet' 54, to limit rotation of the ratchet when" 10 to a-single notch for each stroke of the armature 55.

A cam wheel 1f, having uniformly spaced radially extending projections separated by an equal numbers! serrations or grooves, such that the total number of projections added to the number of grooves equals the number of teeth on the-ratcnetwheeitc; is fixed to one end of the shaft 66. hile'xible follower '-'strlp 12, parallel to base'scand perpendicular to the axis of shaft 65 at; theerid on which the cam 1| is mounted, isffixedat one end to the projection 13 of the-base 55.-and has its-- other end free to move under the action of the A projection 14 directed toward the cam 11 is located on the follower strip 12 directly opposite the axis of 'shaft'fifi'. Projection "14 follows the cam?! and flexes the follower strip 12. Thus when the 'ele'ctro mag'net 5'4 a'cts'on the armature 56, the pawl 61' engages the ratchet wheel 10 and advancesitcne notch. This rotates the "cam wheel an amount corresponding to the angular distance from the center line of a serration to the center line of a projection. If the projection 14 were resting on a serration ofthe cam 1|, a ridge then 'would'move under it, lifting it and flexing thefollower strip 12. The next time the -electromagnet 54 lsenergiz'ed, a-serration of the cam wheel 1| -ismcved under the projection 14. With further activation of the magnet, the cycle is repeated@ I tin contact ringer or strip 15, flexible contact finger 15,- stiff contact finger 11, flexible contactfinger 18 "and stiif contact finger 19 resp'ectivel'y are mounted in parallel'spaced relation above the follower strip 1-2separated from the follower strip and from each other by fiat insulating Spacers. The ends of strips 15 to 19 corresponding to the fixed end of the follower strip 12 are fixed, and the other ends are free to move with "fie'x'ur'e of the strips in a plane perpend'icular to the base.

Flexible contact fingers 16 "and 18 and follower strip 12'- 'are longer than the stiff contacts 15, 11 and 19 and project; beyond them at the ends adjacent the shaft 56'. Insulating spacer is fastened to the freeendof flexible contact finger 18' and in operating contact with flexible contact finger 16. Insulated spacer 8| is fastened to the free nd'of flexible contact finger 16 and in operating contact With follower Strip 12. when the follower strip 12 is raised by the cam 1|, flexible contact 16 is lifted by spacer 8|, bringing it into contact with stifi contact finger 11, and flexible contact '18 is lifted by spacer 80 into contact with. stifi contact finger 19. When a seri ation on the'cam 1 moves under the projection 14 of the follower strip 12, the

iij suajsss follower springs back toward-the cam,-the fiexible contact finger 16 moves from contactwith stiff contact 11 into contact with stiif contact finger l5, and flexible contact 18 moves from contact with stiff contact finger 19 to the open position. When the electromagnet:54 is again energized, the cycle is completed; contact 16 moves into contact with contact 11 and contacts '18 and 19 close. s

For purposes of explaining the operation of the control, let ,us assume that the control has just acted to slow down the motor 25 and-shift control to the'limit H. The 1oop l5 falls until it touches the limit H, at which time the cloth makes contact between the reel 22 and the limit H, completing the circuit including the line 23, the resistance 83, the lead 84,-flexible contact 16, stiff contact finger Tl, leadl9, limit I'Lthe cloth l0, reel 22, lead 2|, starter anode 46 and cathode 44 of the tube 42 and the line 24. This fires the tube 42, completing another circuit consisting of the supply line 24, the cathode and plate 45 of the tube 42, the coil 49 of the relay 43 and the supply line 23, energizing the relay 43. This in turn closes the contacts of the relay 43 and completes a third circuit, including the supply line 23, contacts 41 and 48, coil 53 of the ratchet relay 4|, and the supplyline 24. ,This energizes the ratchet relay 4l,causing thecontacts 18 and 19 to open andthe flexiblefcontact 16 to shift from the position as shown in. Fig. 2 touching contact 71 to a position touching contact finger 15. The opening of the contacts 18 and 79 cuts the fixed resistance 36 into the field circuit of the motor 25, speeding it up... The

shift of flexible contact finger'lB from contact 11 to contact 15 of the ratchet relay performs .two functions. It breaks the starter ,anode circuit of the tube 42, extinguishing it, thus opening contacts 4'! and 48 of relay 43,-and deenergizing coil 53 of the ratchet relay4l Secondly, the shift of fiexible contact finger'lfi transfers control from limit I! to limit l6. -Whe n, after-a lapse of time, the cloth touches the limit 16, the tube is again fired and again activates the relay 43, closing it. This again activates the ratchet relay 4!, which this time closes the contacts 78 and 19 and shifts th fiexible contact 16 from contact finger 11 to contactqfinger I5. Closing contacts 18 and I9 shunts out the fixed resistance it shifts control from thelimit l6 back to the limit ll to complete the cycle. 1

The second action of the ratchet relay, 1. e., shifting control from the limit which has just activated the controller, is one of the more. im-

portant features of the inventionand one which makes it particularly suited to the applications in question. As the cloth travels in'slack condition, it sways from side to side; The loop established by the slack willoccasionally shift forward and back, i. e., the lowermost point of the loop will shift to left or right of the median ofcontacts l6 and IT as shown in Fig. 1. Furthermore, the random roping of the cloth itself causes it to present a very uneven surface to the contacts. For these reasons a controller without the feature of the shifting control would, in this application, chatter incessantly. Shifting the control eliminates any effect from further impertinent contacts between the cloth and the contact roll once the controller has been activated, and forces the .cloth to .pass through a complete cycle before the controller is again activated.

The circuits as shown in Fig. 2 are susceptible of slight modifications without altering the efficiency of the control. Thus with proper modification of the ratchet relay, the relay 43 may be omitted, and the ratchet relay 4! connected in itsplace in the plate circuit of the tube 42. In another modification, resistance 83 may be replaced by a voltage divider connected atone end to lead 23 and at the otherto lead 24. Lead 84 would then tap the divider by means of an adjustable connection, in order that the voltage supplied to the cold cathode tube could be varied slightly.

The controller as set forth herein has several distinct advantages over similar devices. Since it operates on a very slight amount of electricity, (of the order of a small fraction of an ampere) a slight touch of the material to the contact is all that is required to set the control in operationthus the control is quite sensitive to the movements of the slack loop. As explainedabove, due to the design of the contacts, the control is not affected by lateral motion of the slack loop. Due to the incorporation of the ratchet relay in the, manner above described, the device is not overly sensitive to repeated slight contacts caused by the moving material, 1. e., once the contact has been made and the tube fired, a full cycle must be completed before the same contact roll or limit can fire the tube again.

Reference has been made in the above descriptionto cloth saturated with various solutions. It is customary in operations of'the kind described to run the squeeze rolls of the saturator with a pressure setting sufiicient to give extraction, i. e., 90% by weight of moisture on the basis of the dry weight of cloth is present in the cloth as it leaves the rolls of the saturator. Such an amount of moisture is not necessary for the effective operation of the control, it being necessary only to have a slight amount of moisture present above the normal regain value of 9 to 15%.

The present controller has been described as applied to a variable speed D. C. motor moving roped moist cloth. Manifestly, it would work equally well with moist cloth in the open width, or with similar material, suchas, for example, moist paper, or with any material capable of carrying the slight current involved; or a variable speed A. C. motor could be substituted for the shunt motor of the drawings. Or the two motors could be exchanged. That is to say, the constant speed motor may be employed to move the material as it leaves the slack loop. In this embodiment, the variable speed motor is employed to move the material into the slack loop. An-

other variation well within the scope of the present invention is the substitution in place of the variable speed motor shown of a constant s eed motor with a variable speed drive such as a Reeves electric remote control, or a Reeves hydraulic control. In either case the subject con" trol would be arranged to operate the pilot device of the variable speed drive.

What is claimed is:

1. device for controlling an electric D. C shunt motor, comprising a cold cathode tube alternate means for completing the starter anode circuit of said cold cathode tube, a relay activated by the plate circuit of said tube, a second relay 7 having a ratchet and controlled by the first relay, said second relay adapted to alternately inears-ass first y. 9. cold cathode .t be activa ing-sai normally open relay. a contact conn ctin ,the material to the ,starter anode of "the cold k athfe ode tube, .andQaipIui'BIity, off dd tional c 'tacts disposed aboveiand'belowt p th of them te i l w ereby th material ill complete the starter. anode circuitof the coldlcathode' tube ajnd activate the relays; I

3. In a device for feeding anjen dless,lengthpf material from one stationito another, meet for establishing and 'maintainingplack therein V prising in. combination La, constantjsp at the first station,.,a' ,va ablespeed mo second station, "a: relay adaptedlto cut in" and cut, outla-resistar'i'ce in ,th ,e

the variable speed motorga, norm all' open.,type

movin materialla afited-to ots: rial and activatelthe eold i at fljde. tube.

4. In ,cor'nbination'fla co'nstantjlifspeed motor moving an endless length of inoist" cram into. 1' a zone of slack, a variable speed: V cloth on out ofIthe'fzone ofsIa kQfaii'Q'eIect cal contact to connect the cloth to the starter node,

of a [cold cathode tube,two'i'morecontacts isposed one above and. one belowithe-patli'ot'the cloth and. adapted I to coact, with the cloth and complete the starter anode circnit lof' thefcol'd cathode tube, a, normally open type;relay,conitrolled by the anode circuitl'of the cold cathode tube, and a second re'lay' having, a ratchet and adaptedto alternately increaseor deer s the resistance, in the power .T-jcirouit of the. var able Speed or nas mi i lta o slv Shi t the start ranode circuit from one; to the other of the con: tacts disposed above and belowthe cloth.

5. The combination with an npparatus {or processing a moving --1ength of. moist; cloth -pf means for e i$h ntand. ma n n n -slack therein o r sin a-con tant sn d meto i i r liver e ma eria o a s ren po nt: a-.-veriable speed motor to coactawith the first otor and feed th cloth from-the -giyen point subject to the motion of the cloth ror the speed'zof said;secondmotor ncluding va;co 1d cathode tube, alternate contact means disposed above and below the moving cloth to coact with the cloth and complete the starter anode circuit of said cold cathode tube, arelaiy' activated by the plate circuit of-=said itubefl aisecond relay activated by the first relay, said. "second relay adapted to alternately-increase or decrease the resistance in the 'motorci' 'it. andsimultaneously shift the anode circuit f the coldcathode tube from one-to the other-of sald-contactmeans.

6. In combination, a constant spee'd fmotor adapted to move an endless lengthof moist cloth, a variable speed D. C. shunt motor adapted to coact with said constant speed motor and move movin fih he p s cl t i s c qnd t m sa dva b amo s wh ene el .a' fame is sto a e1 d i sai fieldcircnit, a ratchet'relay havingfcon apts e t fswi tenement in e d c e a necite'dparallel with the fixed" resistor, said relay having a'magnetic coil, an armature acted on by "the "coil," and" a' pawl, ratchet and'fcam adaptedjtocoact with the armature to operate mwenta'cts; 'a'circu it including a normally-open tyge 're ayjanu a circuit inclnding the'cathode and'startr anodeof the eem'tatho'de "tube, a per maneiit contact tor the moving cloth," alternate contacts above nd below "thpathf or 'the' cloth nee le"canner t W t h' 9 h n 'aii ate fi seldil Wa e be ia ih vatingfthe fre1ays; and a: second set' of contacts t th were the i et bee a -7. A device ror" htro11 ing an electric D. ,0, hun meter. c mpri in co ca tu e ntjerrjate'i means for completing the starter spa e rcll q l e i 991d a liq -tl a a r la -11 a ra het e i veiedfb he pla circuit .01- are; s i r le afi' cd i 'dra e etely ease or e ree t e res s ance h 'fi r ai mete ;en si nulteheq slv s i ihe a erano ecircuit of th cold cathode tube from one the qilirp sa uit cemen i e n 8; In a device for feeding an endless length; of ma eria imm ta o to, o he m an fo l' ffie is i i ali ma ntai i g Sl c v h e fr fv c9 Dris gin' co'mbinationa constant speedjelectric motonto fe'ed the material from one station, fa'

variable speed electric motor to move the material iritothe receiving station, a power circuit or ihei aria sl ced mot n lud ng a x eisiene l r che r ayhaving contacts a i i ia neti f. qi S conta connec d in nar.a 1e ..w,itntne a cdr istance a ma'll 09 1 rela ha in a el t a n ti 1 9 andi s nt ets Qn rete her y, a c u t nc n the; l the-ratc t r a nd he contact ftbenb rna open el y. 'acol'd ca o be hav zie a te an de circui a df m Circuit, saidplate circuit including thecoiloi the 13 13 mal yi p n relay, an conta ts mounted adjacent the" path of the moving ma'terial connected into th' severance circuit of they cold cathodetnbe. wn epy rne aterialgwm' complete; thestarter anodefcircuit of the cold cathode tube and. jacti at i he a avs- 9,; The combinationvwith an apparatus for processingfiamoving; length "of material, 'of means for establishing and maintaining slack therein com- ,prising a constant speed motor roryrn vifiethe materialbeyond'a fixed point, a 'varia'ble' 'speed motofconstruoted and arranged ftol coaotf'with thelfQ lStant speed motor'aiid'control move ent of theimaterialfas fit 'p'ass e s beyond the ri ed 't,f and/controller means for advancing: and

rheieriae iae 'moerqwh cbyas mo 5 materialmay be held slack Within preledl i is di efi d er mea sincll fl: 1 5 2 1; 11W 9 ii 'ianq fi em l ts m u ted bo c therein avel he ma er land da ts ;.iairm tenily nse ath ma ri aca dea hp e ube a in a st teranode circuit e a-arp e e'; ir ll b (Said, star anod circuit Q QJ E PQQ t rts. .QO lP Qt anormally-flpen typl relay; 'tl le coil o cuit of ,vvhich is, connected to the plate-circuit ofthe cold cathode tube,;1a ratchet type relay the coil circuit of which is connected to the contacts of the normally open 1 l relay, said ratchet relay being adapted to increase or decrease the resistance in the power circuit of the variable speed motor, whereby the contacts upon engagement with the moving material will activate the tube thereby activating the relays and varying the speed-of the variable speed motor.

10. In a device for feeding an endless length ratchet relay, a cold cathode tube having a starter anode circuit and plate circuit, said plate circuit connected in series with'the electromagnet of the normally open relay, a pmrality of contacts disposed above and below the path of said cloth to coact with the cloth and complete the starter anode circuit of said cold cathode tube and activate said relays, and a sec-t 0nd set of contacts on the ratchet relay adapted to shift the starter anode circuit of the cold cathode tube from one set to the other of said contacts above or below the pathof the moving material.

11. In a device for feeding an endless length Of material from one station to another, means for establishing and maintaining slack therein comprising in combination a constant speed driving means and a variable speed driving means arranged in tandem, a relay having an electromagnetic coil, an armature, cam, ratchet and pawl, and contacts operated by the electromagnetic coil coacting with the armature, cam, ratchet and pawl, said contacts connected to the variable speed driving means whereby to increase or decrease the rotational speed of said variable speed driving means on energizing said coil, a second relay having normally open contacts controlled by an electromagnet, said contacts controlling the circuit including the coil of the first relay, a cold cathode tube having a plate circuit and a starter anode circuit, said plate circuit controlling the circuit including the electromagnet of the second relay, and contacts connected to the starter anode circuit of the cold cathode tube and mounted adjacent the" path of the moving material, whereby the material will complete the starter anode circuit of the cold cathode tube and activate the relays.

12. In a device for feeding an endless length of moist material from one station to another, means for establishing and maintaining slack therein comprising in combination a constant speed driving means adapted to deliver the material from the first station, a'variable speed driving means adapted to receive the material at the second station, a relay having an electromagnetic coil, an armature, camfratchet and pawl, and contacts operated by the electromagnetic coil coacting with the cam, ratchet and pawl, one set of said contacts connected to the variable speed'driving means whereby to increase or decrease the rotational speed of said variable speed driving means on energizing said electromagnetic coil, a cold cathode tube having a starter anode circuit and a plate circuit, said asses plate circuit connected in series with the elec tromagnetic coil of the ratchet relay, contact means connecting themoving material to the starter anode circuit of the cold cathode tube, alternate contact means adjacent the path of the moving material adapted to contact the material and complete the starter anode circuit of the cold cathode tube, and a second set of contacts on the ratchet relay,v adapted to shift the starter'anode circuit of the cold cathode tube from one to the other of said alternate contacts mounted ad'jacentthe path of the material.

13. A device for controlling a variable speed electric motor comprising a cold cathode tube having'a starter anode, a plate and a cathode, alternate circuit completing means, a circuit including the starter anode and cathode of said tube and one Of said circuit completingmeans, a normally open type relay having anelectr0- magnetic coil and normally open contacts operated thereby, a circuit including the plate and cathode of the cold cathode tube and the coil of said normally open relay, a relay having an electromagnetic coil, an armature, ratchet, pawl and cam, and contacts operated thereby, a circuit including the coil of the ratchet relay and the contacts of the normally-open type relay, a fixed resistance, a power circuit for the variable speed motor including the fixed resistance and two'contacts "of the ratchet relay connected in parallel, whereby the said contacts will cut the fixed resistance in or out of the motor circuit on activation of the ratchet relay, and a second set of contacts on the ratchet relay connected to the circuit including the starter anode and cathode of the cold cathode tube, and adapted to shift said circuit from one to the other of the aforesaid circuit completing means.

14. In combination, a constant speed motor moving an endless length of moist cloth into a zone of slack, a variable speed motor moving the cloth on out of of the zone of slack, an electrical contact connecting the moving cloth to one side of the starter anode circuit of the cold cathode tube, at least twoelectrodes connected to the other side of the starter anode circuit of the cold cathode tube, said electrodes spaced from the first contact in the direction of the length of the cloth, and spaced above and below the'path of the moving cloth and adapted to intermittent engagement by the cloth, whereby during such engagement the cloth may enter as an electrical conductor into the starter anode circuitof said tube and complete said circuit, a normally open type relay controlled by the anode "circuit of the cold cathode tube,and"a second relay having a ratchet and adapted to alternately increaseor decrease the resistance in the power circuit of the variable speed motor, and simultaneously shift the starter anode circuit from one to the other of the electrodes disposed above and below the path of the cloth.

1 JAMES'C'. RYDER.

v UNITED STATES Parent's Number.

Name a Date 2,185,836 Croco Jan. 2, 1940 2,317,921 Leach Apr. 27, 1943 ,353,639 Berthold et al., July 18, 1944 

